Randomness in Allopatric Speciation

Data from North American terrestrial vertebrates are used to test hypotheses of randomness in several aspects of allopatric speciation (vicariance). The data do not lead to rejection of the following: the initial parapatry of vicariance tends toward randomness as time passes; barriers are random as to affected species (the congruence of barriers is unusual); ranges of geminate species (a pair formed by vicariance) and subspecies (in species with only two) are random in size. The data lead to modification of the following: barriers that lead to subspecific differentiation arise at random places.